The invention relates to renovation of pipelines, such as drainpipes, with a lining technique. The invention particularly relates to branch pieces to be used when branch points are being lined and to lining of the branch points.
Pipe systems, for example drainpipe systems of buildings, are typically renovated by replacing the pipes with completely new ones or by coating the inner surfaces of existing pipes with an appropriate coating technique and coating material. When the pipes in a building are replaced with completely new ones, often structures of the building have to be destructed by chipping, for instance, so that old pipes can be detached from the walls of the building. It is expensive, dirty and time-consuming work to destruct and rebuild wall structures. Because of the noise and dust caused by the renovation work it is often impossible to live in the premises during the renovation work.
Pipelines may also be renovated by coating the inner surfaces thereof. One technique of this sort is a so-called lining technique, in which a liner is slipped into a sewer to be repaired and is impregnated with a special epoxy resin which forms, when hardening, a continuous and leak-proof pipe that is i.a. self-supporting, acid-proof, food-grade and environmentally friendly. The wall thickness of the pipe liner is, depending on the size of the pipe, 2 to 4 mm, and its smooth inner surface guarantees excellent flow properties. The durability, environmental safety and service life of the pipe having been installed in place and hardened are comparable with corresponding properties of new pipes.
Problems in lining are caused by branch points in the pipeline, which also must be lined and made leak-proof. A prior art solution uses a branch pipe sewn of the same lining material that is used for lining the rest of the pipeline. Lining of a branch point begins by cleaning, after which the vertical pipe is lined and the lining is left to harden. The branch point is opened by drilling a hole in the lining of the vertical pipe, the branch piece being then slipped into the branch point and installed in place. Finally, the branch pipe is lined in a partly overlapping manner together with the part of the branch piece that enters the branch. When all the parts have hardened, the result of the work is inspected.
A problem with the arrangement described above is the high probability of a failed installation and a slow installation process involving multiple steps. Taking an epox-impregnated branch piece to the branch point and setting it in place is difficult and time-consuming. Moreover, some of the epoxy easily adheres to the pipes along the way as the branch piece is being taken to the branch point, and, as the epoxy dries, sharp epoxy spikes are left in the already lined vertical pipe, the spikes catching dirt when the sewer is used and thus blocking the pipe easily. Installing the branch pipe requires special tools whose service life extends for some installations only because they get easily caught in the drying epoxy and the tools have to be removed from pipe by force. In addition, the end result of the branch piece installation can only be inspected after the epoxy has dried and the branch piece has settled in place, so a failed installation is extremely laborious and time-consuming to remove.